1. Field of the Invention
This invention relates to valves, particularly valves useful in medical apparatus, and control modules employing valves for controlling medical apparatus during procedures, and, more particularly, to ball valves and control modules employing such valves which are especially useful for controlling surgical procedures requiring irrigation, aspiration and/or control of the pressure within an organ of the body during surgery.
2. Description of Related Art
As noted in U.S. Pat. No. 4,180,074, and related U.S. Pat. No. 4,184,510, the requirements of ultrasonic equipment in surgery, particularly, for example, in surgical procedures requiring aspiration and irrigation, are quite complex and necessitate the precise control of the equipment during these steps. While the two noted patents provide a careful study of the problems encountered and requirements of such control systems, define terms, which definitions are incorporated and used herein, trace the history of such surgeries and equipment which had been used in the past, and provide improved devices and methods for controlling ultrasonic equipment during such procedures; there still exists a need for even more precise control of the equipment during such steps as aspiration and irrigation, particularly during surgical operations as, for example, phacoemulsification and other ophthalmological procedures.
In addition, the use of pinch valves with ultrasonic equipment, as is common, with a switch, usually a foot switch, controlled by the surgeon, often results in an unintended opposite flow of fluid upon the surgeon releasing the switch, with potentially serious results. For example, if the surgical site, such as an eye, is being irrigated with a positive flow of irrigating liquid in or near the eye, a sudden ceasing of the flow may inadvertently cause a negative pressure in the irrigation conduit, and at the tip of the operating end or needle of the handpiece, particularly where the tip is positioned through an incision in the eye, and hence in interocular pressure, resulting in aspiration of fluid including, possibly, aqueous humor. Therefore, there is a need for a device which will provide zero pressure to flow conduits upon the surgeon releasing the switch controlling fluid flow, such as irrigating fluid or aspiration.